Model Extents

The model extent defines the size of the model geometry limits (maximum allowed dimensions).

Operations on geometry require a numeric tolerance (for example, checking if two points are at the same physical location). This tolerance is dependent on the model size. For example, microwave structures may require dimensions that differ by only a few micrometres, but this level of accuracy is not required for studies of antennas on large ships.

The model extents are the same in all coordinate directions. Only a single value, the Maximum coordinate needs to be specified.
Note: The model extents are specified in the model unit.
For example, if the Maximum coordinate is 500, the entire geometry must fit inside a 1000x1000x1000 box centred at the origin.
The tolerance on the model dimensions is determined by taking the Maximum coordinate divided by 5x108. If coordinate values differ by more than this value, the coordinates are considered unique.
Note: Values are only considered to be identical if the distance between them is less than a hundredth of the model tolerance. (Between these values is a range where the uniqueness and connectivity cannot be guaranteed.)
The default value for the model extents is 5E+02 (500). It is recommended that this value is used, except in the following cases:
  • When modelling a large object in a small unit, for example, an automobile in a model unit of mm.
  • When high accuracy is required. If the model is never larger than 5 units, it is recommended to reduce the model extents to 5 instead of using the default of 500.
Attention: For extent settings other than the default value of 500, exported Parasolid models will not be in the same unit as used in CADFEKO.

The extents box limitation applies to all geometry.

For example, an intersection between two spheres cannot be performed if either sphere exceeds the size box even if the resultant intersection would be within the extents boundary.